Various systems have been employed to make a gas-fit fireplace realistically resemble a burning log fire. Currently systems are known wherein burning illuminating gas is fed up from some form of substrate, such as through a sand bed, which is heated to incandescence by the burning gas to resemble a bed of coals, the burning gas also passing up and around a synthetic log made of refractory material. The visual simulation of a burning log can be very effectively and realistically simulated by such methods; however, the sound of a crackling fire is characteristic absent. Although electronic sonic generators and loudspeakers may readily be configured to generate such sounds to add realism, such approaches are expensive, and essential parts of the system cannot be safely placed within the radiant heat zone of the fireplace. An economical solution to this problem, and in particular a sonic generator which can withstand elevated temperatures in the immediate vicinity of a fire, has yet to be provided.